A feature of the wheel hub assemblies presently in use is that whenever the wheel hub of a vehicle is under the level of water, as is common for boat trailers submerging to launch or retrieve a vessel or a caravan subjected to flooded crossings, water enters the hub housing and penetrates to the bearings located therein. The water enters because it exerts a higher external pressure on the sealing lip of the hub seal than the gas pressure resident within the hub itself, so distorting the lip of the seal and allowing water to enter the hub. As a result, the lubricant within the hub becomes contaminated with water which spreads to the bearings and causes oxidation and rapid deterioration of the wearing surfaces of the bearing assemblies.